1. Field of the Invention
The subject invention relates to a filter cartridge for use in fluid filtration, and more particularly, to a filter cartridge configured to provide two or more levels of fluid filtration.
2. Background of the Related Art
Many residential, industrial and healthcare applications require the fluid used therein to be filtered prior to use. For example, in the United States, residential public water supplies are commonly treated with various chemicals, such as chlorine, to disinfect the water and avoid potential adverse health effects. However, these chemicals can have an undesirable effect on the taste and odor of the water, and may not provide the level of cleanliness desired for consumption. Consequently, many residences now filter their tap water or purchase bottled water for cooking and drinking.
Not all fluid applications within a residence require the same level of filtration or conditioning, nor is it cost effective to treat all of the water to the same degree. For example, the water used in washing the family car or for watering the lawn does not require the same level of filtration as potable water. Additionally, it may be desired to provide water having a specific or distinct level of filtration or softness for dish washing, bathing or the laundry. Therefore, in a residence it is desirable to provide water having two or more levels of filtration.
There is also a need to provide two or more levels of fluid filtration in other applications, such as in industrial or healthcare applications. In the healthcare industry, fluids administered parenternally to a patient must to be filtered prior to administration. Typically, filtration of a parenternal fluid is achieved by passing it through a filter apparatus which includes a porous medium. In some protocols continuous or long term administration of several parental fluids is required and each fluid is passed through the same filter apparatus, along the same flow path and through the same porous medium. There are disadvantages associated with the use of a single if flow path and providing a single level of filtration for all administered fluids. For example, the same porous medium may not be suitable or equally efficient for processing different parenternal fluids.
Traditionally, only one level of filtration or conditioning can be obtained from a single filter cartridge or assembly. In such filters, unfiltered fluid enters into the cartridge through an inlet port, passes through filter media disposed within the cartridge and discharges through a single outlet port. These traditional filter cartridges may contain multiple media types, but the fluid traverses through the media over a single flow path, resulting in flow through all media in turn or in series.
In residential applications, one method of obtaining two levels of filtration from a single filter assembly has been to provide an assembly that is configured to allow the user to select between filtered water or unfiltered water, as disclosed for example in U.S. Pat. No. 5,744,033 to Bertrand. Another solution consists of adding components to the filtration system or assembly, or more particularly, by designing manifold systems which utilized platforms and multiple filter cartridges. U.S. Pat. No. 5,107,896 to Otto is an example of a manifold-type system that achieves a second level of filtration by adding filter cartridges to the system. However, increasing the number components, increases the system complexity, cost and space requirements.
There is a need, therefore, for a fluid filtration apparatus having a cartridge which is configured to simultaneously provide two separate discharges of fluid from a single source, each discharged fluid having been subjected to a distinct level of conditioning or filtering. By providing two levels of filtration from a single filter cartridge, the need for additional hardware can be eliminated, thereby simplifying the installation and maintenance of the fluid treatment system and reducing the number of components required.
The subject invention is directed to a new and improved dual-flow filter cartridge that includes a housing, a first stage filter and a second stage filter. The housing defines a central axis and an interior cavity and includes an inlet portion for receiving fluid into the interior cavity, a first outlet portion for discharging fluid from the interior cavity, and a second outlet portion for discharging fluid from the interior cavity.
The first stage filter is disposed within the interior cavity of the housing for conditioning fluid passing therethrough and is in fluid communication with the inlet portion and the first outlet portion by way of a first flow path. The second stage filter is also disposed within the interior cavity of the housing and conditions the fluid passing therethrough. The second stage filter is in fluid communication with the inlet portion and the second outlet portion by way of a second flow path.
The filter cartridge further includes a mechanism for selectively directing the flow of the fluid through the interior cavity of the housing. The mechanism is configured to selectively direct the flow of fluid through the first flow path, in which fluid traverses through the first stage filter and exits the housing through the first outlet portion. The mechanism is also configured to direct the flow of fluid through the second flow path, through which fluid traverses the first stage filter, the second stage filter and exits the housing through the second outlet portion. Alternatively, the mechanism can direct the flow through the first and second flow paths simultaneously. In a preferred embodiment, the mechanism for selectively directing the flow of the fluid through the interior cavity of the housing is positioned external to the filter cartridge housing.
In a preferred embodiment, the first stage filter and the second stage filter are coaxially positioned relative to one another within the interior cavity of the housing. In this embodiment, the first stage filter has a hollow core and the second stage filter is disposed within the hollow core of the first stage filter. Typically, the first stage filter includes at least one filter media for conditioning the fluid. The filter media can be a sediment-type filter (e.g. resin bonded cellulose), a carbon block filter, a hollow fiber filter or any other media suitable for filtering fluid or a combination of media types. In this embodiment, it is envisioned that the first flow path is substantially radial within the interior cavity of the housing through the first stage filter.
The second stage filter also includes at least one filter media for conditioning the fluid. The at least one filter media can be a hollow fiber filter media or any other media suitable for filtering fluid or a combination of media types. In this embodiment, it is envisioned that the second flow path traverses through both the first and second stage filters, substantially in the radial direction within the interior cavity of the housing through the second stage filter. Alternatively, the second flow path only traverses the second stage filer.
Preferably, the filter cartridge further includes a structure for directing the flow of fluid through the first flow path and the second flow path. In one embodiment, the structure is defined by an end cap disposed within the interior cavity of the housing and has surfaces dimensioned and configured for directing the flow of fluid within the housing. In this embodiment, the end cap can be positioned at the base of the filter media or at the top of the filter media, or in both locations. In another embodiment, the end cap is disposed within the filter media, for example, at the mid-height or thereabout.
It is envisioned that the structure for directing fluid through the first flow path and the second flow path is integral with the housing. However, it can be a separate and distinct member that can be inserted into the interior cavity or removed as desired.
The subject invention is also directed to a filter apparatus which includes a head and a filter cartridge. The head having an inlet flow port, an outlet flow port, means for securing the head in fluid communication with a fluid supply, and fixture for securably attaching a filter cartridge to the head. The filter cartridge includes a housing which defines a central axis and an interior cavity. The housing has an inlet portion for receiving fluid into the cavity, a first outlet portion for discharging fluid from the interior cavity, and a second outlet portion for discharging fluid from the interior cavity.
Preferably, the filter cartridge also includes, a first stage filter disposed within the interior cavity of the housing for conditioning fluid passing therethrough. The first stage filter is in fluid communication with the inlet portion and the first outlet portion by way of a first flow path. A second stage filter is also disposed within the interior cavity of the housing for conditioning fluid passing therethrough. The second stage filter is in fluid communication with the inlet portion and the second outlet portion by way of a second flow path which differs from the first flow path.
In this embodiment, the filter apparatus further includes a first outlet flow valve for selectively controlling the discharge of fluid from the first outlet portion of the housing and a second outlet flow valve for selectively controlling the discharge of fluid from the second outlet portion of the housing. Preferably, the first and second outlet flow valves are positioned external to the filter cartridge housing, but are fluidly connected thereto.
In yet another embodiment, the filter apparatus includes a device for selectively blending the fluid discharged from the first outlet portion and the fluid discharged from the second outlet portion. The blending thereby forming a single discharge of fluid having selected filtration properties. In a preferred embodiment, the device blends the fluid discharged from the first and second outlet portions of the housing and includes a valve. The valve includes a first inlet port for receiving fluid discharged from the first outlet portion of the housing, a second inlet port for receiving fluid discharged from the second outlet portion of the housing, and a discharge port for discharging the blended fluid. Alternatively, the valve can include, a third inlet port which receives fluid which has not been passed through the filter apparatus. As before, the blending forms a single discharge of fluid having selected filtration properties.
The subject invention is also directed to a method of filtration which includes the steps of supplying fluid to a dual-flow filter cartridge, and passing the fluid through the filter cartridge. The dual-flow filter cartridge of this embodiment includes a housing defining a central axis and an interior cavity, a first stage filter and, a second stage filter. Preferably, the housing has an inlet portion for receiving fluid into the cavity, a first outlet portion for discharging fluid from the interior cavity, and a second outlet portion for discharging fluid from the interior cavity.
The first stage filter is disposed within the interior cavity of the housing for conditioning fluid passing therethrough and providing a first level of filtration. The first stage filter is in fluid communication with the inlet portion and the first outlet portion by way of a first flow path. The second stage filter is disposed within the interior cavity of the housing for conditioning fluid passing therethrough and providing a second level filtration. The second stage filter is in fluid communication with the inlet portion and the second outlet portion by way of a second flow path and further conditions the fluid which has passed through the first stage filter. Alternatively, the fluid bypasses the first stage filter and is only conditioned by the second stage filter.
It is envisioned that the filtration method of the subject invention further includes the step of selectively directing the flow of fluid through the filter cartridge housing such that the fluid traverses through at least one filter stage. In a preferred embodiment, the step of selectively directing the flow of fluid through the filter cartridge housing includes regulating by valve means the discharge of fluid from the first outlet portion and from the second outlet portion.
The subject application is also directed to a filter cartridge that includes, inter alia, a housing defining a central axis and having an inlet port for receiving fluid into the housing. The housing also having a first outlet port for discharging a first fluid from the housing, a second outlet port for discharging a second fluid from the housing, and an interior cavity.
In this embodiment, a first stage filter has a hollow core and is axially disposed within the interior cavity of the housing and conditions the first fluid. The first stage filter communicates with the first outlet portion by way of a first flow path which is substantially radial through the first stage filter. Additionally, a second stage filter is axially disposed within the hollow core of the first stage filter, the second stage filter conditions the second fluid and communicates with the second outlet portion by way of a second flow path. The second flow path is substantially radially inwardly directed through the second stage filter.
Those skilled in the art will readily appreciate that the subject invention allows for greater selectivity in fluid filtration than prior art filtration devices, without increasing the number of components in the filter assembly or the space requirements. These and other unique features of the filter apparatus disclosed herein will become more readily apparent from the following description, the accompanying drawings and the appended claims.